Effect of High Temperature on Fruit Productivity and Seed-Set of Sweet Pepper (Capsicum annuum L.) in the Field Condition

Abstract

Chili peppers grow best and are likely to reach the maximum yield at temperature ranging from 21 °C to 33 °C. In the plastic house, the temperature increases to 42 °C in the summer. The fruit set and fruit growth were effected correlative with the high temperature condition. In this study, Shishito peppers were grown in plastic house in two periods (in the early stage of April and the end stage of May) in 2012. The difference in temperature between two periods of planting was about 4 °C. In fruit set period of the 2nd planting, the weather condition is disadvantage for fruit growth. During temperature changed in the summer, the fruit weight and the number of seeds per fruit of both “Shishi-homare” and "105c-10" varieties were reduced about 0.5 and 2.8 times in the 2nd planting when compared with the 1st planting. The number of seeds per fruit reduced corresponding with the fruit size under the high temperature condition.

Full text

Journal of Agricultural Science and Technology A and B
& Hue University Journal of Science 5 (2015) 515-520
doi: 10.17265/2161-6256/2015.12.010
Effect of High Temperature on Fruit Productivity and
Seed-Set of Sweet Pepper (Capsicum annuum L.) in the
Field Condition
Tran Loc Thuy1 and Murakami Kenji2
1. Department of Plant Protection, Cuu Long Delta Rice Research Institute, Can Tho 900000, Vietnam
2. Department of Bioproduction Science, Ishikawa Prefectural University, Ishikawa 921-8836, Japan
Abstract: Chili peppers grow best and are likely to reach the maximum yield at temperature ranging from 21 °C to 33 °C. In the
plastic house, the temperature increases to 42 °C in the summer. The fruit set and fruit growth were effected correlative with the high
temperature condition. In this study, Shishito peppers were grown in plastic house in two periods (in the early stage of April and the
end stage of May) in 2012. The difference in temperature between two periods of planting was about 4 °C. In fruit set period of the
2nd planting, the weather condition is disadvantage for fruit growth. During temperature changed in the summer, the fruit weight and
the number of seeds per fruit of both “Shishi-homare” and 105c-10 varieties were reduced about 0.5 and 2.8 times in the 2nd planting
when compared with the 1st planting. The number of seeds per fruit reduced corresponding with the fruit size under the high
temperature condition.
Key words: High temperature, seed-set, fruit productivity.
1. Introduction
The origin of pepper (Capsicum annuum L.) is
Mexico and the neighboring areas of Central
America. Shishito is one of four popular sweet
pepper cultivars (Hushimi-ama type, Shishito type,
Bell type and F1 type) in Japan [1]. Fruit is small,
green and non-pungency. In Japan, The crop of sweet
pepper begins in the last stage of spring and harvests
from May to November [2]. During this time, the
temperature increased strongly, when the extreme
temperature of more than 40 °C sometimes was
recorded in August [3]. Under plastic house in the
field, the inside temperature will be higher.
Temperature strongly influenced the development of
fruit and flowers of chili pepper [4]. The optimum
temperature for chilli pepper cultivation is 21-33 °C.
Low and high temperature condition affect the size
of fruit and seed germination ability [5, 6]. Under
Corresponding author: Tran Loc Thuy, Ph.D. student,
research field: plant production.
changing of weather, temperatures are higher than
the optimum chili’s growing, thus the plants are
objected to disadvantageous temperature period [7,
8].
In general, high temperature influences many
aspects of plant physiology and growth, which may
lead to significant losses in crop productivity in
many species due to limited vegetative, reproductive
growth and seed yield [9]. According the survey of
Erickson and Markhart [10], fruit set and
productivity of pepper reduced during periods of
high temperature. High temperature frequently
occurs after anthesis of chilli pepper and strongly
impacts the reproduction and yield. However, the
rare investigation about the effect of high
temperature on chili pepper crop has been elucidated.
Therefore, the present study aimed to study the
impact of high temperature during summer period in
Japan on the phenological and morphological
character of fruits of Shishito pepper.
D
DAVID PUBLISHING

Effect of High Temperature on Fruit Productivity and Seed-Set of Sweet Pepper
(Capsicum annuum L.) in the Field Condition
516
2. Materials and Methods
The experiment was carried out in plastic house of
Okayama University, Japan. Four varieties derived
from Shishito (Capsicum annuum L.), viz.,
“Shishi-homare” (a favorite variety in Japan),
“105c-10” (low-pungent mutation line derived from
“Shishi-hormare”), “Kounou Shishito” and “Kairyo
Shishito” were used in the current experiment.
The seeds were sown in sowing tray in both the
planting times. The 1st time was on April 9, 2012 to
August 16, 2012, “Shishi-homare” and “105c-10” were
planted in this time; and the 2nd time was on May 30,
2012 to October 30, 2012, four varieties were planted
and filled with commercial soil (300 mg/L N, 450 mg/L
P and 370 mg/L K). During the 1st planting, the pots
containing the seeds were kept in the growth chamber,
which set at a daily 16/8 h (light/dark) with a
temperature of 28/20 °C, respectively. After three weeks
when seedlings were at 3-4 leaf stage, 30 seedlings of
each variety were transplanted to plastic pot (10.5 cm,
containing commercial soil) and kept in the plastic
house, and distance between two pots is 15 cm. At
anthesis stage, 10 plants of each one were transplanted
again to the ground in plastic house. The distance
between two plants was 50 cm and the distance
between two rows was 1.2 m. The seedlings were
trained with two main branches. Depending on the daily
temperature, plants were watered once or twice per day.
The plants were supplied with fertilizer of NPK fertilize
(20 g/m2), and Ca and Mg (80 g/m2 each), respectively.
Temperature in plastic house was recorded with
thermocouples connected to data-logger. The plant
growth situation before the 2nd transplanting was
recorded. All the individual flowers were labeled for
finding the days after flowering (DAF). Fruits from
flowers of 28-30 DAF were harvested with one fruit
per branch weekly. The morphological characteristic
of harvest fruits (fruit size, fruit diameter, fruit length)
and number of seeds were recorded. Fruits from
labeled flowers were harvested once per week from
the last of June to the middle of August for the 1st
planting and from middle of August to the end of
October for the 2nd planting. The data obtained were
analyzed following Tukey-test (P ≤ 0.05).
3. Results and Discussion
The temperature in plastic house increased
gradually from April 15th, and the highest temperature
of 42 °C was recorded from the early August to the
early September (Fig. 1). During the 1st planting
period (Fig. 1a), the temperature averaged from 28 °C
to 33.4 °C in day and 11.8 °C to 21.4 °C at night,
which gradually increased and reached a peak of
42 °C in the early August. The temperature increased
nearly 4 °C from the 1st planting to the 2nd planting.
The 1st flower in the 2nd planting appeared in the
late July, when the maximum temperature is about
41.6/24.6 °C (day/night) (Fig. 1b). The difference in
temperature between the 1st planting (the early stage
of June) and the 2nd planting for the 1st flower
opening was 7 °C.
No significant difference was observed between
“Shishi-homare” and “105c-10” in the number of days
to the 1st flowering. When the temperature increased,
the days to the 1st flower reduced, respectively (Table
1). Similar results were reported by Qumer et al. [11].
No significant difference was observed in the node
number in all the varieties during both planting times.
This might be because all the varieties belong to
Shishito group, and thereby exert similar
morphological characteristics.
The fruit size of harvested fruits, such as fruit
length, fruit weight, fruit diameter and seed number
per fruit were recorded in Table 2 and no difference
was observed in the fruit weight, fruit length, fruit
diameter and seed number per fruit between
“Shishi-homare” and “105c-10” in the 1st planting.
But when the temperature increased in the 2nd
planting, the morphological characteristic of fruits in
all varieties changed, fruit weight and number of seeds
per fruit of both “Shishi-homare” and “105c-10” were
reduced about 0.5 times and 2.8 times, respectively.

Effect of High Temperature on Fruit Productivity and Seed-Set of Sweet Pepper
(Capsicum annuum L.) in the Field Condition
517
(a) (b)
Fig. 1 The temperature condition during culture of two times planting.
E: the early stage of month (1st-10th), M: the middle stage of month (11th-20th), L: the last stage of month (21st-30th).
Table 1 The number of days to the 1st flowering, the node number of the 1st flower and the plant height in the 2nd
transplanting.
Plant time Variety Days to the 1st
flowering
The node number of
the 1st flower
The height in the 2nd
transplanting (cm)
1st planting Shishi-homare 57.8 ± 0.9a 15.1 ± 0.7
b
15.4 ± 0.8c
105c-10 56.6 ± 0.7a 14.3 ± 0.6
b
15.9 ± 0.62c
2nd planting
Shishi-homare 53.4 ± 1.7
b
15.0 ± 0.8
b
17.0 ± 1.0c
105c-10 52.3 ± 1.1
b
15.1 ± 0.7
b
18.0 ± 0.7
b
c
Kounou Shishito 53.2 ± 0.8
b
16.9 ± 1.0a 21.8 ± 1.1a
Kairyo-Shishito 52.6 ± 1.3
b
15.1 ± 1.0
b
19.0 ± 1.1
b
a-cDifferent letters within the same column indicate a significant difference at 5% level by Tukey’s test.
Table 2 The morphological characteristics of harvested fruits at 28-30 DAA.
Plant time Variety Fruit weight (g) Fruit diameter (cm) Fruit length (cm) Numbers of seed/fruit
1st planting Shishi-homare 8.9 ± 5.1
b
1.6 ± 0.4
b
6.8 ± 2.2
b
51.8 ± 33.1
b
105c-10 8.9 ± 4.9
b
1.7 ± 0.3
b
6.8 ± 2.1
b
54.1 ± 34.9
b
2nd planting
Shishi-homare 4.3 ± 1.6a 1.2 ± 0.2a 5.0 ± 1.1ab 18.3 ± 23.58a
105c-10 4.5 ± 1.2a 1.3 ± 0.2a 5.2 ± 1.5ab 19.9 ± 18.9a
KounouShishito 3.9 ± 1.6a 1.3 ± 0.3a 4.6 ± 1.3a 25.3 ± 25.1a
KairyoShishito 4.4 ± 2.1a 1.3 ± 0.3a 4.9 ± 1.9ab 27.0 ± 22.3a
a and bDifferent letters within the same column indicate a significant difference at 5% level by Tukey’s test.
The chili peppers grow best and are likely to reach
the maximum yields at temperature from 21 °C to
33 °C [3]. After the 1st flowering in the 2nd planting,
the temperature increases fluctuating from 37 °C to
42 °C, and thereby affects the fruit weight. The fruit
diameter and fruit length in the 2nd planting were
smaller than these in the 1st planting. Among the
varieties, fruits of “Kounou Shishito” are the smallest
in shape. In 1982, Ali and Kelly [12] reported that
fruit weigh, fruit length and fruit diameter of sweet
pepper reduced in the high temperature conditions. In
Shishito pepper, fruit weight reduced significantly and
seeds per fruit was lowered under high temperature
(38/30 °C day/night) [13].
The morphological characteristics of fruit were
strongly affected under high temperature (Fig. 2). The
highest fruit weight and fruit length were recorded on
July 8 in harvested “Shishi-homare” fruits of the 1st

Effect of High Temperature on Fruit Productivity and Seed-Set of Sweet Pepper
(Capsicum annuum L.) in the Field Condition
518
planting (Fig. 2a). In both “Shishi-homare” and
“105c-10” varieties in the 1st planting, fruit weight,
fruit diameter and fruit length reduced rapidly after
July 22, 2012, which correlates with the increase
temperature at this time. The fruit weight reduced
strongly responding to high temperature in both
“Shishi-homare” and “105c-10” varieties.
In the 2nd planting, the 1st flower appeared when
the temperature stayed in high condition (37.8/24 °C,
day/night), after that the temperature increased rapidly
(a) (b)
(c) (d)
(e) (f)
Fig. 2 The change of morphological fruit under two temperature regimes of two times of planting.

Effect of High Temperature on Fruit Productivity and Seed-Set of Sweet Pepper
(Capsicum annuum L.) in the Field Condition
519
and remained a long time. It correlates with the
development of four morphological fruit varieties
when the fruit weight, fruit diameter and fruit length
were small in the 1st harvested time and decreased
gradually. After September 14th, fruit weight, fruit
diameter and fruit length begun to increase, but it was
still smaller than that in the 1st planting. The
“Kounou Shishito” variety had the smallest fruit
weight and fruit length (Fig. 2d and 2f) in almost
harvested time.
During the 1st flower appearing in the 2nd planting,
the temperature condition fluctuated in 33-42 °C, thus
the weight of fruit was effected. When the weight of
fruit decreases, the diameter and the length of fruit
will reduce, correlatively. The diameter and the length
fruit in the 2nd planting were smaller than that in the
1st planting. Thus, all of Shishito varieties in this
experiment were impacted by high temperature.
In Japan, the annual temperature has been
increasing at rate of 1.1 °C per century since 1898. As
temperatures rise, the numbers of days with the
minimum temperatures ≥ 25 °C and the maximum
temperatures ≥ 35 °C are increasing, respectively [14].
In plastic house, the temperature is higher than outside.
High temperature (≥35 °C) has kept in long time
since the early of June. The highest temperature in
plastic house was 42.05 °C, which was recorded by
thermocouples. Shishito pepper grew best under the
field and green house with temperature ranging from
21 °C to 33 °C [3, 13]. Field and controlled
environment observations of pepper production
indicate substantial abortion of floral buds occurs
when day temperatures are ≥34 °C and/or night
temperature are ≥ 21 °C. Thus, when the maximum
temperature per day was ≥ 34 °C during the
day and night temperature ≥ 21 °C in early stage of
July (Fig. 1a), the fruit weight, fruit diameter, fruit
length and number seed of fruit decreased rapidly until
the lst harvest of the 1st planting and the almost
harvest time of 2nd planting. Fruit developed under
over the suitable condition, therefore harvested fruits
from the 2nd planting were smaller than that from the
1st planting (Fig. 2 and Table 2). Exposure to high
temperature, from microspore mother cell meiosis of
pepper flower to tetrad dissolution, in greatly reduces
pollen viability and anther dehiscence [15]. High
temperature inhibits the development of pollen grains
during the period of final tetrad formation to tetrad
dissolution. The reduction of pollen viability
effectively reduces fruit size and fruit set [10]. After
fertilization, the fruit size was determined by cell
divisions and cell expansions. The Shishito pepper
fruit width was the most sensitive to high temperature
until 10 DAF and less effected from 30 DAF
onwards [13]. Exposure to high temperature
throughout fruit development significantly reduced
Shishito pepper fruit weight. The reduction of fruit
length and fruit diameter responds the reduction of
fruit size in the high temperature condition in the 2nd
planting stage.
The reduction of seed numbers per fruit may have
been partly responsible for the reduction of fruit size.
A positive correlation was observed between fruit
weight and number of seeds per fruit of sweet pepper
[10, 16]. In the 2nd planting, under the high
temperature condition when the fruit weight
decreased, the seeds/fruit reduces in the same way.
Besides, under high temperature condition, the
reduction in the number of viable pollen affect
fertilization capacity, hence reducing number of
seeds per fruits. After fertilization, abortion of seeds
during the initial stages is probably due to failure in
proper cell division, which might due to high
temperature [13]. Thus, numbers of seed in all
varieties reduced strongly in the 2nd planting
compared to the 1st planting.
The results indicated that a significant response of
Shishito pepper was observed under high temperature
condition in the summer. Fruit quality of Shishito was
reduced drastically. Thus, managing the time to
sowing and harvesting is necessary for growing chilli
pepper.

Effect of High Temperature on Fruit Productivity and Seed-Set of Sweet Pepper
(Capsicum annuum L.) in the Field Condition
520
4. Conclusions
The morphological fruits (the fruit weight, the fruit
diameter, the fruit length and number of seeds per fruit)
under high temperature decreased strongly. The
results indicated a significant difference in the
response of Shishito when the temperature increased
in the summer. Fruit quality of Shishito reduced
clearly in bad condition for growing. Thus, managing
the time to sowing and harvesting is so necessary
when growing sweet pepper.
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